I don't recall that this card's bios could be modded.
It is modded with Hawaii Bios Reader and HEX redactor. It gives plus abt 0,5 mh/s. Real good
hashrate increase for R9 290/390 you can achieve in Linux with opensourced amdgpu driver. Unfortunately AMD doesn't make good official drivers for old cards. It is their and Nvidia policy aiming to sell new cards for profit.